Three-toed box turtles are actually a native species to the United States. They travel - a lot. Space is a great necessity. The more you can provide, the happier your 3-toed will be. I keep mine in a hard plastic kiddie pool that measures 4.75 feet across. It's a simple set-up with enough bedding that he can easily burrow in and become completely invisible. This bedding must be kept moist (not sopping) or he will protest by sleeping in his water dish. He has his own pool (a small litter box) that gets cleaned daily, and a log hide that he often chooses to sleep in. Even with this much space he often patrols the perimeter.
3TBTs are omnivorous, meaning they eat plants and animals. They love variety and many absolutely love tomatoes. In the wild they are known for destroying gardens with their voracious appetite for tomatoes. They may stop eating if you offer the same thing every day (they get bored - wouldn't you?). I've tried commercial box turtle hard food and mine won't touch it. He does seem to like the TetraMin SoftGel (smells like apple), which he gets every other day in addition to his other assortments. He loves tomatoes and melon, but won't eat grapes or "box turtle yummies" moist snacks. I try to give him something a little different every day, always fresh or frozen/thawed. He much prefers fresh. He likes crickets too, but they tend to escape as there is no lid on his home.
The water dish should be big enough that the turtle can easily get in and out to soak, drink, and potty. A kitty litter box works very well for a single turtle. The water should be deep enough to reach the top of the legs, but no deeper. Remember, they aren't aquatic and can't swim! If you see your three-toed box turtle laying in the water dish with their head down, don't be too quick to panic. My turtle sometimes sleeps in his water dish. Because the turtle drinks the same water that they soak and potty in, it does need to be changed daily, and sanitized no less than once a week.
My 3-toed box turtle is a male. His head and eyes are orange. This is the easiest way to tell gender, but it's not fool-proof. Some females in rare circumstances have red eyes too. The only fool-proof way to know is to bring your turtle to a herp-veterinarian.
When considering a box turtle, gender is a big deal. A lone male or a lone female are just a good. If you want two box turtles, they need to both be female. If you put one male and one female in an enclosure together, the male will nag the female (wanting to breed) until they're so stressed out that one or both could actually die. It's suggested that if you are going to keep a male with females, you should have at least three or more females and a very large enclosure with lots of hiding places to assure he doesn't bother the girls too much. If you live in a warmer climate, it's suggested that you make a safe enclosure outside to give them more space. Unfortunately, northern Minnesota is frequently too cold for an outdoor enclosure, so mine is in the house.
As with any captive-kept turtle, if yours is indoors you will need to provide a basking light with appropriate UV rays (UVA and UVB). A UVB 5.0 should be appropriate for an indoor box turtle. If you aren't able to provide steady hours of daylight for your turtle, please consider purchasing a timer to turn your lights on and off every twelve hours. Your turtle will appreciate it.
Sometimes box turtles will naturally go into hibernation. As long as your turtle is healthy, let it happen. Hibernation is natural and helps to keep them healthy. My three-toed box turtle hibernates during the summer because with the air conditioning on it's colder in the house in the summer months.
Every three-toed box turtle has an individual personality. A note about my guy in particular - he is a strange turtle. He loves to have his head rubbed and will actually lean in to let you pet him. He doesn't mind having his feet messed with and he almost never hisses (unless you wake him up - but I'm grumpy when someone wakes me up too). He also loves his water dish. He enjoys soaking in there for hours at a time. If you walk by or sit near his cage, he will come to the side to check you out and see what you're doing. He actually looks at you when you talk, which is actually a little creepy, but gives him character none-the-less. When he eats, he will use the backs of his front legs to wipe his face, much the way small children do!
Three-toed box turtles only get to be 4-6 inches long. Well cared for box turtles can easily make it to 80 years old (or more). Please do your research before committing to bringing one home - chances are it will outlive you!